Method of synthesizing aliphatic mercaptans and sulfides



Patented Aug. 24, 1948 UNITED STATES METHOD OF smnnsrzma ALrPnA'rIc MERCAPTANS AND- SULFIDES Richmond 1 Bell and cal-1151s M. Thacher, Highland Park, 111., as'signors to The Pure Oil Company, Chicago, lit, a corporation of Ohio No Drawing. Application December 31, 1943, Serial No. 516,548

21 Claims.

Another object of the invention is to provide a method for preparing alkyl sulfides.

Further objects of the invention will be revealed by the following description.

We have discovered that if hydrogen sulfide and unsaturated acyclic hydrocarbons are contacted with commercial anhydrous aluminum chloride in the presence of anhydrous hydrogen chloride,

the hydrocarbons react readily with the hydrogen sulfide to form mercaptans and sulfides. The relative proportions of mercaptans and sulfides which form are dependent upon the temperature at which the reaction is carried out, the length of time of contact and the relative proportions of hydrogen sulfide and hydrocarbons present in the mixture.

Reaction of hydrogen sulfide with oleflnes may be carried out at temperatures from approximately 35 C., to approximately 150 C. The reac-' tion proceeds readily within the range of atmospheric temperature, but for production of mercaptans satisfactory results are achieved at temperatures in the vicinity of 0. .Reaction may be carried out at pressures ranging from approximately atmospheric to 500 pounds per square inch or more. We have found that pressures of approximately 100 to 200 pounds per square inch are very satisfactory.

Our invention is applicable to the preparation of mercaptans and alkyl sulfides from olefins such as ethylene, propylene, butenes, pentenes,yoc'tenes and dodecenes. Mercaptans prepared in accordance with our invention are useful in the synthesis of alkylated benzene and in the preparation of synthetic rubber.

Our invention may be carried out batch-wise I 2 I olefin and catalyst may be charged to a vertical reactor equipped with means for efllcient agitation, and maintained at a desired temperature and pressure for a given period of time, Hydrogen. sulflde and hydrogen chloride are passed through the reaction mixture and any excess is recycled. After the desired contact time has elapsed, agitation is stopped and sufilcient time is allowed for the reaction mixture to separate into two layers, an upper product layer and a lower catalyst complex layer. The upper layer is drawn off through an exit line in the side of the reactor above the interface level, and is hydrolysed by acidified water. The organic productsseparated from the hydrolysis are treated with weak sodium carbonate solution to remove hydrogen sulfide and hydrogen chloride. Another charge of olefin is then introduced and agitation, together with introduction of hydrogen sulfide and hydrogen chloride, resumed. This procedure can be repeated until catalytic activity hasreached a negligible value, and at this time thecomplex layer as well as the last upper layer prodnot is withdrawn and hydrolysed either separately or together with the upper layer. Mercaptans and sulfides may be separated from unreacted olefins by conventional methods of distillation and/ or extraction, and the unreacted olefins be used for part of the charge stock. I

Another method of more continuous operation achieves agitation by circulation of-the liquid re action mixture as long as the complex phase re-,- main sufiiciently fluid. Aluminum chloride may, be charged to a loosely packed vertical reactor containing a screen at the bottom to retain alumi-r num chloride until liquid complex is formed. Liq-. uid olefin may be charged'in the top of the tower and hydrogen sulfide :and hydrogen chloride in the bottom of the tower. Liquid is circulated from the bottom of the tower to the top and hydrogen sulfide is added only in sufficient amount to maintain the pressure. Products may be continuously withdrawn from the circulating stream, and the heavier catalyst complex may be separated from the less dense products by mechanical means such as centrifuging. Liquid complex is returned to the system and liquid products arecontinuously hydrolysedby counter current treatment with water, preferably acidified. Organic products separated after hydrolysis maybe continuously washed free of hydrogen sulfide and hydrogen chloride by counter-current treatment with weak sodium carbonate solution followed by water washing. Mercaptans and sulfides may be separated from the finished product by distillagen sulfide to 1 part of oleflne, although it will be understood that we are not limited to these pro- In either batch or more continuous operation contact times may vary over as wide a range as several minutes to several days although in general operation in a continuous manner is more satisfactory with short contact times, determined by the relation of charge rate, temperature, and the extent of conversion.

The amount of hydrogen chloride gas present in the admixture may vary from 0.01 mole to 1.0

portions. Good results have been obtained using mole per mole of aluminum chloride. proportions of one mole of hydrogen sulfide to 2 In order to demonstrate the efiicacy oi simoles of oleflne to 2 moles of hydrogen sulfide to 1 multaneous use of aluminum chloride and hydr mole of oleflne. gen chloride in the formation oi. mercaptans and In the preparation of mercaptans from low sulfides from hydrogen sulfide and olefinesa seboiling olefins such as ethylene, reaction proceeds rles of runs was made using hydrogen sulfide and more rapidly at temperatures of 0 C. and below, ethylene as the reactants. A run was made in with low formation of sulfides. With increase of which no catalyst was used. Other runs were temperature there is a tendency for alkyl sulfides I made inwhich aluminum chloride alone was used to form at the expense of mercaptans. but such as the catalyst. One run was made using hydrotendency can be reduced by shortening contact gen chloride as the catalyst, and two runs were times. At low temperatures such as 0 C. and a made using aluminum chloride together with hycomparatively short contact time of 17 hours, an drogen chloride as catalyst. The runs were made increase in the ratio of hydrogen sulfide to olefin in a bomb having a capacity of 850 c. c. and were i'avors mercaptan formation, but at C. and a carried out at pressures ranging from 100 to 200 long contact time of '72 hours there is a marked 25 pounds per square inch. In making the run the tendency toward sulfide formation when the hyb was swept t ith nitrogen gas prior to drogen sulfide to olefin ratio is increased. In the charging t catalyst and th ea tants, After case of ethylene, high yi of er p can be the catalyst and reactants were charged to the O e at p at s f approximately bomb in desired proportionathe bomb was a1- with a hydrogen Su fi to ethylene ratio of 2 t0 1 lowed to stand for a desired period of time after moleswhich the .vapors in the bomb were very slowly Although mercaptan yields of 30% theoretical released through a washing and absorption train. can be obtained with case from ethylene and hy- The data on the runs are listed in the fouowmg dfogen sulfide at temperatures of apprfaximatelfi table. Although the temperature of the runs is g g" :2 g can be g shown as 25 C. the runs were all made at atmosg i" n ng o 8 or examp w m cm 6 pheric temperature and th temperature varied triisobutylene, yields in the neighborhood of 75% 1 theoreti 1 e bt i bl t im t 1 20 mm 21 27 during the runs :3 C at o a 8 approx e y In the runs made prior to run E-32, the reac- Although the higher boiling olefines react with 4 mm gases dlspharged fijom the bomb were allowed to pass 111 a fine dispersion through a long greater ease than the lower boiling olefines and column (600 c. c.) of water opped with 100 c. c. therefore lower temperatures may be used. We f d i d t ab b mm mm prefer to use temperatures of approximately 20 to o n 5 d 30 C., that is, ordinary room temperatures, in the mercap ans an Y1 su es mm 9 gas synthesis of mercaptans from olefines having 8 Stream The j q was water'washed or more carbon atoms to the molecule, since large and extracted wlth decalm- Startmg yields of mercaptans with only small amounts of 3 5 column 9 aqueous 506mm carbonate alkyl ulfid are produced lutlon topped with solvent naphtha, (Stoddard The ratio of catalyst to reactants may vary solvent) was used instead of the water topped widely. The larger the amount of catalyst pres- 50 wlth decalm, smfle It was found that T sodium cut the greater the quantity of products formed Carbonate 501151011 would Substantlally and hence the larger the conversion. Aluminum pletely remove e hydrogen Sulfide a t e Stodchloride may be mixed with the reactants in d Sol ent uld o b the ptans and amounts ranging from 0.05 to 1.5 moles per mole sulfides. Mercaptan sulfur was determined in of olefine in a batch operation, or per mole of the solution by the silver nitrate method and sulolefine initially present in the reaction zone in fide sulfur was determined by the bromine-water more continous operation. method.

Yield, Per Cent of Charge Moles Catalyst Contact Temp, Theoretical sulfur Run H28 C2114 Time/Hrs. G. No.

Kind Moles Mercaptans Sulfides 0.00 0.00 None 0.00 1,296 25 0.2 13-12 0.10 0.21 0.10 11 0 11.0 3.0 13-98 0.11 0.11 0.10 18 0 22.3 5.1 E-69 0.24 0.12 0.10 11 0 31.1 2.1 E-87 0.11 0.22 0.10 14 25 13.8 1.9 E-96 0.10 0.10 0.10 12 25 10.2 12.8 13-8 0.24 0.12 0.10 so 25 as 20.1 12-02 0.10 0.10 0.10 12 25 1.1 0.0 15-32 0.11 0.11 0.10 4 25 11.4 0.2 15-12 0.24 0.11 0.10 5 25 10.0 1.1 12-12 0.10 0.10 0.10 24 25 0.0 0.0 13-112 0.10 0.10 0.10 24 25 11.2 3.0 13-111 0.10 o. 10 g: 24 25 11.5 2.3 12-113 0.12 0.12 g: 21 25 18.0 4.1 11-34 I hydrogen sulfide to ethylene as It will be observed from the table that hydrogen chloride gas alone does not catalyze the reaction. Aluminum chloride alone on the other hand is a good catalyst. The effectiveness of aluminum chloride to produce either mercaptan or sulfide is dependent on the time oi contact, temperature and the relative proportions of hydrogen sulfide andethylene charged to the bomb. With a contact time of approximately 24 hours or less aluminum chloride caused the formation predominantly of mercaptans with a small amount of sulfide. This tendency to form the mercaptan in preference to the sulfide was enhanced by increasing the ratio of hown by runs E-98, E-69 and E87. On the her hand long contact times promoted the formation of sulfides as shown by runs E8 and E-32. Contrary to the effect of high ratio of hydrogen sulfide to ethylene at short contact times and low temperatures, the efiect was just the reverse with 4 long contact times and higher temperatures as shown by runs E-96, E-8 and E452.

The marked effect of having hydrogen chloride gas present in the reaction mixture is shown by runs E-84 and run 113. The increase in the mercaptan yield is very marked.

It will be seen, therefore, that by catalyzing the reaction 01' olefines and hydrogen sulfide with aluminum chloride in the presence of hydrogen chloride a marked increase in the yields of mercaptans and sulfides, but principally mercaptans, over those which are obtainable in the presence of aluminum chloride alone is effected.

It is claimed:

1. The method of synthesizing aliphatic mercaptans and sulfides from hydrogen sulfide and olefinic hydrocarbons which comprises chemically reacting a mixture of hydrogen sulfide and olefinic hydrocarbons in contact with anhydrous aluminum chloride in the presence of anhydrous hydrogen chloride the molal ratio of olefinic hydrocarbons to hydrogen sulfide being within the limits of 10:1 to 1:10.

2. The process in accordance with claim 1 in which the hydrogen sulfide and olefinic hydrocarbons are reacted at a temperature of approximately -35 C. to 150 C.

3. The method in accordance with claim 1 in which the olefinic hydrocarbon is ethylene.

4. The method in accordance with claim 1 in which the olefinic hydrocarbon is propylene.

5. The method in accordance with claim 1 in which the olefinic hydrocarbon contains 12 carbon atoms.

6. The method of synthesizing aliphatic mercaptans from hydrogen sulfide and olefines which comprises chemically-reacting a mixture of hydrogen sulfide and olefines at a temperature between approximately 35 C. and 150 C. in contact with catalyst consisting only of anhydrous aluminum chloride and anhydrous hydrogen chloride the molal ratio of olefines to hydrogen sulfide being within the limits of 2:1 to 1:2.

'7. The method in accordance with claim 6 in which the olefine is ethylene.

8. Method in accordance with claim 6 in which the aluminum chloride is suspended in or dissolved in a non-aqueous organic liquid diluent which is inert to the extent of taking no substantial part in the reaction.

9. Method in accordance with claim 6 in which the aluminum chloride is present in the reaction mixture in an amount not less than about 0.01

mole per mole of olefine.

10. Method in accordance with claim 6 in which the hydrogen chloride is present in an amount not less than 0.01=-mole per mole of aluminum chloride.

11. Method in accordance with claim 6 in which the aluminum chloride is present in the reaction mixture in an amount not less than about 0.01

mole per mole of olefine and the hydrogen chloride is present in the reaction mixture in an amount not less than 0.01 mole per mole of aluminum chloride.

12. Method in accordance with claim 6 in which the aluminum chloride is present in the reaction mixture in an amount between 0.05 and 1.5 moles per mole of olefine and the hydrogen chloride is present in an amount between 0.01 and 1.0 mole per mole of aluminum chloride.

13. -Method in accordance with claim 6 in which the mole ratio of olefine to hydrogen sulfide is from 2 of the former to 1 of the latter to 1 oi. the former to 2 oi! the latter, the aluminum chloride is present in the mixture in amounts of 0.05 to 1.5 moles per mole of olefine and the hydrogen chloride is present in the mixture in amounts of 0.01 to 1.0 mole per mole of aluminum chloride.

14. The method of synthesizing aliphatic mercaptans from hydrogen sulfide and unsaturated acyclic hydrocarbons containing at least 8 carbon atoms in the molecule, comprising contacting a mixture of hydrogen sulfide and unsaturated acyclic hydrocarbons with anhydrous aluminum chloride in the presence of anhydrous hydrogen chloride at temperatures of approximately 20- 30 C.

15. Method in accordance with claim 14 in which the aluminum chloride and hydrogen chloride constitute the sole catalysts.

16. Process in accordance with claim 15 in which the reaction is conducted under pressure of approximately -200 pounds per square inch.

17. Process in accordance with claim 14 in which the unsaturated acyclic hydrocarbons are predominantly C12 hydrocarbons.

18. The method of synthesizing C12 mercaptans comprising contacting a mixture of acyclic unsaturated hydrocarbons, composed chiefiy of C12 hydrocarbons, and hydrogen sulfide at a temperature of approximately 20-30 C. and under superatmospheric pressure in the presence of anhydrous aluminum chloride and hydrogen chloride as the sole catalysts.

19. Method in accordance with .claim 18 in which the aluminum chloride is present in an amount between .05 and 1.5 moles per mole of olefin. Y

20. The method of synthesizing ethyl mercaptan comprising reacting ethylene and hydrogen sulfide at atmospheric temperature and under superatmospheric pressure in the presence of anhydrous aluminum chloride and hydrogen chloride as the sole catalysts for a period of time not in excess of approximately 24 hours.

21. Method in accordance with claim 20 in which the mole ratio of ethylene to aluminum chloride is not less than 1 to 1 and the mole ratio of hydrogen sulfide to ethylene is not less than 1 to 1.

RICHMOND "1'. BELL. CARLISLE M. THACKER.

(References on following page) 7 l 8 REFERENCES ermn Number Name Date 2,137,584 Ott Nov. 22, 1938 The following references are of record in the 2 295 99 Otto Sept 22, 1942' file of this Patentr 2,352,435 Hoefielman June 27, 1944 UNITED STATES PATENTS 5 23664453 Meadow J51}. 2, 1945 Number Name Date OTHER REFERENCES 1,836,183 Nlsson Dec. 15, 1931 Thomas, Anhydrous Aluminum Chloride" in 2,052,268 Williams Aug. 25, 1936 Organic Chemistry, Reinhold, New York, 1941,

g 2,101,096 Reuter Dec. 7, 1937 10 pages 867, 868. 

